CVE-2026-53027 fs/ntfs3: fix missing run load for vcn0 in attr_data_get_block_locked()
A missing run load in the Linux kernel NTFS3 driver causes a warning and potential crash when handling compressed or sparse attributes.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-53027?
CVE-2026-53027 is a medium-severity vulnerability in Linux kernel, published on 24 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: fix missing run load for vcn0 in attr_data_get_block_locked()
When a compressed or sparse attribute has its clusters frame-aligned, vcn is rounded down to the frame start using cmask, which can result in vcn != vcn0. In this case, vcn and vcn0 may reside in different attribute segments.
The code already handles the case where vcn is in a different segment by loading its runs before allocation. However, it fails to load runs for vcn0 when vcn0 resides in a different segment than vcn. This causes run_lookup_entry() to return SPARSE_LCN for vcn0 since its segment was never loaded into the in-memory run list, triggering the WARN_ON(1).
Fix this by adding a missing check for vcn0 after the existing vcn segment check. If vcn0 falls outside the current segment range [svcn, evcn1), find and load the attribute segment containing vcn0 before performing the run lookup.
The following scenario triggers the bug: attr_data_get_block_locked() vcn = vcn0 & cmask <- vcn != vcn0 after frame alignment load runs for vcn segment <- vcn0 segment not loaded! attr_allocate_clusters() <- allocation succeeds run_lookup_entry(vcn0) <- vcn0 not in run -> SPARSE_LCN WARN_ON(1) <- bug fires here!
Which versions are affected by CVE-2026-53027?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53027?
Apply the vendor's patch.
Is CVE-2026-53027 being exploited?
There is no known exploitation of CVE-2026-53027 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-90552, BELL-CVE-2026-53027, DEBIAN-CVE-2026-53027, GHSA-mcqq-386f-gvf4, ROOT-OS-DEBIAN-12-CVE-2026-53027, ROOT-OS-DEBIAN-13-CVE-2026-53027 and 2 more.